Definatly max WIS,CON and Dex!
Also if you are going to dual class and you are going to dual wield I think you would be wise to put 3 points into 2 weapon style. the thaco0 penalties of dual wielding will eventually be rough when you are no longer advancing your berserker levels. I agree that flail is the best choice to start with. Hammer is a great 2nd choice (you can dual wield 2 of the best weapons a cleric can wield with that combo).
I made the same decision as you just recently. I was going to go with a berserker dualed to a cleric then I fell in love with the ranger/cleric. I gave up the cool berserk ability (and I cannot put more than 2 points into a weapon) but in return I can cast any druid spell in addition to the cleric spells
also rangers start with 2 points 2 weapon style.
Oh I would recommend you stear clear of sword and shield style. No need to waste points in defense against missile weapons when you can put points into weapons you want to use.
And as you probably gathered from the rest of the posts hagimihale had it backwards. Only humans can dual class and you can only use a kit by dual classing (no mutliclassing with kits) so you will have to go human to make your berserker cleric.